subplate rigidness and mounting options

[Mlbz420]

I have a blanchard ground aluminum subplate 14 X 33 x 1- 3/8. it is bolted directly to the machine table in each corner so 4 bolts total.

my question was, being that it is twice as long as it is wide should there be some kind of bolt in the middle?

after looking up previous posts about sub plates and how they expand im wondering if the center of my plate is rising as it expands faster than the table itself, it must. would adding a center row of bolts do more harm than good?

My second question is, does using a sub plate reduce the rigidness of a setup? if im doing some heavy milling in a vice bolted to a sub plate will i see any adverse effects? particularly given that the center isnt held down.

First thing tommorow morning the plate is coming out while i clean the machine and check some things and im debating whether i should put it back in. it came with my machine and the previous owners used the plate to hold 3 chick quicklock vises and mostly drilled holes with the machine.

I dont really need it. most of my parts go into vises or get bolted on top of fixtures so i wont miss it if it is causing me any problems. I do like using studs and bolts instead of t-nuts though.

 

[masome]

I would add 2 or 3 more sets of holes, but that might just be me. I like to overdo things sometimes.

 

[shoff]

Even with more bolts, Aluminum subplates scare the crap out of me. Way to much movement with temperature changes.

 

[doug925]

Aluminum sub's work fine for most stuff I do.
I have no problem with temp changes, b/c I have 90 gallons of coolant that is keeping things pretty steady temp wise.

Also, I am not removing 10's of tons of steel before it leaves the enclosure.

MLBZ,

If you can, add a few bolts..
I promise it will not hurt


Doug.

 

[doug925]

Aluminum sub's work fine for most stuff I do.
I have no problem with temp changes, b/c I have 90 gallons of coolant that is keeping things pretty steady temp wise.

Also, I am not removing 10's of tons of steel before it leaves the enclosure.

MLBZ,

If you can, add a few bolts..
I promise it will not hurt


Doug.

 

[Mickey_D]

I use an old 1" thick subplate that I grab with a pair of vises. A lot of what I do is small plastic parts cut out of sheet stock so being able to use quick clamps/c clamps/welding vise grips is a big plus. When I am done it is a whole lot easier to just unclamp the subplate and flip the vise jaws than lifting the vises in and out. Plus if I really screw up the code the machine has to chew through the subplate before it gets to anything expensive like a vise or the machine table.

 

[Mlbz420]

i tool the plate off today. the table and the underside of the plate have a half circle shaped stain starting from center and falls off the back edge. there was also more coolang sludge in that area. the rtest of the table looks pristene.

the staining and puddling tells me either the plate was warped or rising up from expansion. i also see a spot or two where the previous owner used a bolt that was a couple threads to long.

the suspected warped portiion is right inbetween my two vises. so i can see a rigidity problem.

after i have time to check the plate for flatness i may add a couple holes and throw it back in. maybe send it out to blanchard for a skim.

If you can, add a few bolts..
I promise it will not hurt

i cannot contain my laughter...........really....

but seriously, at the moment i am removing a lot of hard stainless. I want to run the rest of the order without the plate and see if there is any difference. ill post back any findings.

in the meantime any other suggestions or experiences?

has anyone tried a black oxide coating on a steel plate? how does it hold up to the coolant? what are your experiences with steel plates and rust?

 

[krazyglue]

Steel is about 40 lbs a board foot.

It gets heavy.

Whats your max table load?

How fast do you want to corner?

 

[Anvil]

If your subplate is made out of Mic6 aluminum tooling plate, it is very thermally stable, more so than most steels and about equal to cast iron.

 

[Mlbz420]

I have no idea what kind of aluminum it is. all the markings were blanchard ground off before i owned it.

fwiw when i took the plate out the mounting studs and nuts were all a little on the loose side. i just retorqed them a week or so ago too cause i notice they were loose.

 

[Edster]

I bought a Jergens Ball lock subplate and a few aluminum fixture plates from them. I just finished a drilled and tapped fixture plate that fits the ball lock subplate. I made it out of freemax 15 that was madison ground and squared up. I didn't tap the holes all the way through so the studs didn't damage the table.

http://www.ewwenterpriseinc.com/FadalVMC15.html

I did use 3/4" aluminum plates from jergens to mount two 6" Kurt vises. I do think they are a little less rigid than mounting directly to the table. I want to replace the 3/4 aluminum with 1" Freemax. I think that will solve the problem.
I really like the ball lock setup. I've had it over a year now and no problems, and it's really easy to change from a vise to a fixture, etc.